1. Technical Field
The present disclosure generally relates to severe duty buckets used with industrial equipment and, more particularly, to floors used with loader buckets used to move hot slag or other extreme materials. Specifically, the disclosure relates to the structure of a flat, monolithic floor for a hot slag bucket, hot slag or extreme buckets using the floors, and methods for retrofitting older hot slag or extreme buckets.
2. Background Information
Slag is a byproduct of both ferrous and nonferrous ore smelting operations. Slag is used for various industrial and commercial purposes. To process slag, it must be moved from place to place while the slag is extremely hot. The hot slag is moved with industrial mobile material handling equipment in many instances using a hot slag bucket. Although there have been ongoing attempts to design and build or retrofit buckets to operate in harsh or high-temperature conditions, repeated operations in a hot slag environment subjects the buckets to cyclical heating and cooling. Current-design slag buckets quickly warp and become so misshapen that they become ineffective for the purposes intended and repair or rebuild of the bucket during the bucket's useful life is often required. These conditions are disruptive to the work effort and expensive to complete. In response to the cyclical heating and cooling caused by the handling of hot slag, the bottoms of most bucket floors will warp to a degree where the bucket must be removed from use and either refurbished or scrapped altogether which significantly increases disruptions to production and increases costs to the owner. The severe warping is believed to be caused by the cyclical heating and cooling of the bucket floor/edge combination that is made from at least two pieces of different-thickness material and/or materials that are different in composition and joined together with a weld joint. These different elements heat and cool and expand and contract differentially to the high heat from the hot slag and eventually render the bucket useless.
An exemplary prior art flat-bottomed slag bucket is indicated generally by the numeral 2 in FIG. 1. Bucket 2 generally includes a floor assembly 4, a pair of side plates 6, and a wrapper 8. Floor assembly 4 includes a rectangular floor portion 10 having a bottom surface. An edge 12 is welded directly to the front of floor portion 10 to form floor assembly 4. Edge 12 may be provided in different configurations such as the straight edge depicted in FIG. 1 and others such as modified spade edges. A typical floor portion 10 may be one inch thick while edge 12 may be provided in a two inch thickness. The different thicknesses of floor assembly 4 contribute to the uneven heating/cooling of floor assembly 4 which leads to the undesirable warping. The continuous weld joint 14 that connects edge 12 to floor portion 10 also heats at a rate that is different from floor portion 10 and edge 12 which also contributes to the stresses heat imparts to materials. The undesirable warping occurs as materials expand and contract at different rates when subjected to the heating and cooling cycles and the stresses that are induced into the materials as a result. When the purchase cost, maintenance costs, and rebuild costs are considered, bucket 2 currently costs as much as $60 per hour of use over its expected life when bucket 2 is used with hot slag operations. Expected bucket life is also impaired.
Spaced skid plates may be welded to the bottom surface of floor portion 10 where they are positioned behind base edge 12. FIG. 4 shows the different thicknesses for floor portion 10 and edge 12. The existence of the long weld 14 that connects edge 12 to floor portion 10 and the different thicknesses of edge 12 and floor portion 10 or different material composition contribute to the significant warping when bucket 2 is subjected to differential cyclical expansion and contraction experienced when bucket 2 is used with hot slag.
Those who manufacture, own and use hot slag buckets have attempted solutions in the past but have not been able to resolve the warping caused by differential heating and cooling or significantly reduce the operating cost of the bucket with their attempts. One exemplary failed attempt is depicted in FIG. 5 where a series of spaced thick and thin curved reinforcing ribs (or gargoyles as these are known in the art) are welded to the inside of the bucket. The gargoyles are added with the expectation that they will reinforce and stiffen the floor of the bucket and prevent warping. These efforts have failed. FIG. 5 depicts an example of how the gargoyles were ineffective at solving the warping problem. The bucket floor is warped to a degree that the middle portion of the front of the bucket is raised significantly above the front corners. Hot slag buckets with added gargoyles such as the examples shown in FIG. 5 have been found to warp well before the end of the expected life of the bucket thus rendering the bucket unfit for its intended purpose. The warping significantly raises the cost of owning and operating a hot slag bucket and the industry desires a solution.